Elevatable load platform for vehicles



y 1952 N. B. NEWTON EI'AL ELEVATABLE LOAD PLATFORM FOR VEHICLES 4Sheets-Sheet 1 Filed Sept. 15, 1949 M/rzwrae's #0:; e. Amt roman cW/elzs672 max y 1952 N. B. NEWTON ET AL 2,603,454

ELEVATABLE LOAD PLATFORM FOR VEHICLES 4 Sheets-Sheet 2 Filed Sept. 15,1949 4 free/var July 15, 1952 N. B. NEWTON ET-AL ELEVATABLE LOADPLATFORM FOR VEHICLES 4 Sheets-Sheet 4 Filed Sept. 13. 1949 PatentedJuly 15, 1952 ELEVATABLE LOAD PLATFORM FOR VEHICLES Noel B. Newton,London,v and Charles Samuel RobertsStock, Slough, England; said Stockassignor to said Newton Application September 13, 1949, SerialNo;,115,380

.- In Great Britain October 2, 1948 I This invention relates toelevating apparatus, that is tosay apparatus having a platform or otherloadfreceiving member which can be raised and lowered and which can beused for lifting heavy articles fortransport, loading or other purposes.The invention is particularly applicable to. transportable elevatingapparatus embodying a wheeled chassis on which it may be moved aroundfor receiving, transporting and delivering heavy articles, such usebeing now generally known as mechanical handling. 1

In order to have a wide range of use, where the load-receiving member isa platform, such platform must be capable of beinglowered close to theground'and of being raised to a considerable height,'and the platformmust have a high degree of stability both transverselyandlongitudinallyin all positions of elevation to allow for unequal distribution of loadthereon, as'must inevitably occuiiduring'loadingor,unloading. f

' Parallel linkag'e'jsystems are well known for the purpose ofcontrolling the leve'Lff'or example of the" platform of a lifting "jack,but "their control varies with variationofiangularity of their linkage,which becomes relativelyineifective as the linkage systemieachesalignment or substantial alignment and moreover apart from suchconsideration of control, a serious manufacturing problem is metwhere-such linkage systemcis required to pass ithroughjjthe position ofalignment of its links, as' willbejexplained later in more detail. 1

For some purposes, the load-receiving member insteadof being a platform,maybe inflthe form of a jib so as to operate as acrane, ,for'rai'sin'g'a load in suspension, the] jib being. mounted in the same'manner as theplatform so that its inclination oruprightness remains the same insteadof varying as-withanormal crane'jib'. This feature has considerableadvantages'fonexample' to enable the machine to be used to raise anengine for fitting to a vehicle chassis, ior' to raise a heavy chuck orjig for fitting to'a'ma'chine tool as the overhang of the upperend-of'the jib does not vary relative to the arm of the jib' as thesame, is raised or lowered. i I

According to the invention-elevating apparatus comprises a base, anelevated "superstructure on the base, a platform, parallel bell cranklevers.

pivotally mounted on the superstructure inter mediate of their ends,each such lever" being pivotally connected by one end to the platformforming a primary parallel: linkage system and their other and shorterend'sb'eing pivotally cons lit I 1 $Qass r P r e 13 Claims. (01. 254-)linkage system, and mechanical lifting means mounted on the base andconnected to the bellcrank lever system.

The elevating apparatus aforesaid may include length'compen'satin'gmeans connecting the platform to the primary linkage system, thesecondary linkage system being soarranged that it does not passthrough'the position of alignment as the platform is raised and lowered;or means for varying the length of a member of the secondary linkagesystem whereby the levelof the platform may be varied in any of itspositions of elevation, the length compensating means permitting theprimary linkage to pass through its position of substantial alignment.

In the accompanying drawings:

Fig. 1 is a side elevation of one example of an elevating platform truckmade in accordance with the present invention;

Fig. 2 is a rear elevation, and f Fig. 3 is a plan of the truck shown inFig. 1;

Fig. 4 is a diagrammatic side elevation showing a modified constructionas a crane;

Fig. 5 is a diagrammatic side elevation showing a further modificationof the invention.

As shown in Figs. 1-3 of the drawing, the elevating platform truckcomprises a chassis consisting of longitudinal framemembers a and crossmembers a and having a pair of front wheels b and a pair of rearcastorwheels c.

The rear cross member a" has a pair of lugs a welded to it for receivingthe lower end of a hydraulic jack unit a At the rear end of the chassisis a superstructure of angle members consisting of rear uprights d,forward inclined up-. rights d top longitudinal'members d and diago:

nal bracing d Attached 'to' the top members d are pairs of rearandforward' bearing brackets e and e. At the rear of the chassis is-ahandle pivotally connected to the uprights d and adapted to be securedas'shown in full lines for use in manoeuvring the chassis, or adapted asshown in dotted lines to be lowered for use as a tow-bar; the handlehaving a cross bar f forming a hand rail.

The platform consists of a sheet metal top 9 attached to a frameconsisting of longitudinal angle members 9 and front and rear anglemembers g g Across the centre of the frame is a further angle member 9where the weight of the platform and its load will be taken. Fixed onthe inside of each'longitudinalmember g are blocks g carrying afixedspindle g The'platform is adapted to be raise'dtand lowered by asystem of bell-crank levers, arranged 4 platform to be tilted slightlybackwards or forwards respectively. This tilting would not be possiblewithout the interposition of the shackles m with the eccentric placed asshown. Another bers i and to a cross tube 2' and by welding the forwardends of the membersi to a further cross tube 2". The tube 2' is providedwith, bushes i to form hearings on the fixed spindle g The arms" 2' arealso braced by a cross channel member i to which are welded lugs irortheju penend of the v hydraulic jack unit a The other armoftheforwardbell crank lever is formed by a pair ofwebs i welded to the centre, ofthe top tube 2' and inclined bracing members i welded at their ends to,the webs and to the ends of -the members A triangulating bracei is alsoprovided between the webs i and the member i 'Ifhe tube 2'? is providedwith end bushes; not; shown, by which it is mounts-don a shaft e? fixedin 'thebrackets e 'The'rear bell-crank lever whichis pivotally n'ountedatthe brackets e; e consists'of downwardl'y extending channel'niem'b'ers' k which at their upper ends'aresecuredto the ends of ashaft, 7c" journaled inthe: brackets e, e; Near the centre of the shaftare welded the other arms of the bell-crank consisting of a pair ofwebslc which are supported by inclined bracing members k welded at theirends to the webs k andto the members is. The lower ends of the membersis are pivotally connected. at'ki to shackles m pivoted attheir otherends to brackets g attached to the ends of the cross member 9 of theplatform structure. 7 V L The upper ends of the webs i 'and 70 areconnected by a'link n, the connection to k being through an eccentricWhichis'rotatable by means of. a lever Ontherearicrossmemher a, ismounted a hydraulic pump 0 for. actuating the hydraulic.'jacka the: pumpbeing manually operable. byitsileverpfl I In operation, as shown in Fig.I, with the lever, 11' centrafpositionthe effective length of the link nis such that theline, joining the, axes of the shaft k andfp'ivotjc isparallel to the. line joining theaxes' ofl'the shafts/e and i andthusthe'lin'ks kand cranked linksi z'f formwith the platform frameand thesuperstructure members (Fa parallel link system; hereint'ermedtheprimary' parallel 'link' system, assuming for the momentlthat theshackles mare notfr'ee to swing. similarly thewebS if andW-areparallelandwith the link 11 and superstructure. members dE form another andsecondary parallellink system. Because the two systems embody thebell-crank construction above described they are positively;

coupled for simultaneous movement and therefore the shackles m havetheir positions. positively defined so that in all positionsof theplatform they are vertical. Thus it is readily the second ary parallellink'system which; through the bell is to be noted that this secondarylink system at no time passes through. a position of alignment of itslinkage. As shown moaned lines in Fig. 1 it becomes obvious that bymoving the eccentric cranks determines thelevel of the platform. It,

to. rear. o'fl'a', law er; truck .It

important function of the shackles m is to facilitate the passage of theprimary parallel linkage system'through the position of alignment of itslinkage When the axes of the shaft k and pivot k are in line with theaxes of the shafts e and 21 'In such position, but for the shackles m itwould be essential that the lengths of the linkage members should beabsolutely accurate or very high stresses could arise unless there wasslack at the, joints of the system. The interposition of the shacklesobviously obviates any such -stressesawhile atthes'ame time so linkingthe rear endiof: platform to the members It thatthe platform level is inthis position and all other positions positively controlled by thesecondary linkage system. J p 7 It is also to beobserved-f'romtheconstruction that-the platform load is directly'suppor'ted by thecranked arms-z--i{- from its transverse centre so that only theunequally distributed loadis taken by the other members of the two;linkage systems; which load-will offcourse be greatest when loading andunloading from the front of the platform. Lateral mal disltributionofload-will be taken mainly by the pairs'of members forming the crankedarms ie-i through the great rigi'dity provided by the constructionwhich-includes especiall'y' the torsional; strength'of' the tubes- 1?,-i3 and i v It will be obvious that the-liack a could be.- otherwiselocatedtharr as; shown and operably crank linkage system. H I

Ina-a modification, as'shcwn in Fig; 4ia short.- ened platform framep'is empioyed, to. which is attached a jib. of triangulatedrigidiconstruction consisting of arms p, p ihavingtheir upper ends joined tocarrya suspension hook q. O'bviously,, of. course,. it. wouldbe'possible to provide sockets on the platform of the arrangementdescribedgin Fig. 1 to receive'the legsof jibwhiclr could be attachedthereto when assessor removed. when not required; As the platform frameis keptievel" as in the example firstidesfcr edlit. wilfbeLeIear that:the inclination of'tlie arm pi'; 1;? remains. constant inall'positfonsso that theioverhang of the 1160 q relative to such arms and to theplat;- form frame. remains. constant Thus, the crane niayzbe. usedtolift anfengiheJout-of or intoa. vehicle. chassis While suspended from.the hook q.. It will be seen that theflebf'centricl'ever 11... may beused provide slight raising or lowering of the; liook'throu'g-h tilting;if; the, platform. frame; p. The, overhangof'the.cranejiblbeyondtheforward. shaft i does ofi'co'urse "fin-posestresseson theparan'eijunkage, systemihsflaswould be caused byl'oadl at.the forward end of: theDIatf'o -m plate g connected to some other memberof the: bell I of the first'example. Y

As showniirFi'g'. 5,.the lifting deviceisattaehed' h i mm esa base'qadapted to be clamped to the rearendsof the frame members r oftheyehicle chassis; The ase! a h s Pairs o eef @B rward b cke s-cf,andllq corresponding, to the brackets. e andle of: i- 1. P le; e biank;.1e r nr-- struction is the. same as that of Fig; 1 and as: W fi' s-fa med be l cr k ssemb y s, n a beli era ikaasse bner w nton-1' e si'nlsu' w n h arms-s and The fa e esis 9 a ear; pq t on v andforward;portion 1) which are articulated but so that the accen s heel of theparttvr can-lockin the'manner of a rule joint under the part '0. Theforward part 11" is connected by a shackle 'wfto the arm t; In addition,complementary lugs s and (1 are provided so that apin may be inserted tohold the arm s in the raised position. As shown dotted, thelrear-portionmay be raisedto form the tail board .for.the end of the truck. :L'Ihehydraulic cylinder :1: is: mounted between the base 'q' and the arms.s..v "1'; I "in use, the part 1; may be lowered into line with the Ilpartviz-and both parts willform aaplatform which can be raised andlowerd;while carryinga load. ..The:hydraulic pressure forll thecylinder-x may be provided from the engine powerli-o'f the vehicle, ashas been done for a hydraulically actuated tipping truck. The level ofthe platform during raising and lowering will be controlled in the samemanner as described for the first example. Tilting for the platform maybe provided by an eccentric located either at one of the pivots of thelink it or perhaps more conveniently at the pivot of the arm .9 to theparts of the platform, but such arrangement is not shown. I

The invention is obviously not limited to all the constructional detailsof the example above described in so far as such details may be modifiedwithout departing from the nature of the invention. For instance othermechanical means than a hydraulic jack could be used for providing theelevating force; such means could be power actuated instead of manuallyand the apparatus could be mounted on a stationary base or some otherbase instead of a wheeled chassis as shown and described.

One advantage of the improved construction of elevating apparatus isthat it has a high factor of elevation combined with maximum levelcontrol of the platform or other load-receiving member.

A further advantage is that it enables a parallel linkage system to beused, part at least of which is capable of passing through the positionof alignment of its links but modified to overcome the aforesaidmanufacturing problem and without loss of level control for theload-receiving member, and by this means a shorter linkage system can beused.

A still further advantage where the load-receiving member is a platform,is to enable the platform to be given a controlled inclination tofacilitate loading on to and from the platform, or as a means of fineadjustment for raising or lowering a suspended load.

What we claim is:

1. Elevating apparatus comprising a base, an elevated superstructure onthe base having front and rear sides, a platform at the front of saidbase, pairs of bell crank levers pivotally mounted at the upper part ofthe superstructure on each side thereof, said bell crank levers beingpivoted intermediate their ends on horizontally spaced pivots, the rearlever of each pair being outside of the front lever, so as to be able topass the same, one arm of each lever extending forward and downward andbeing pivotally connected to the platform at horizontally spaced pointsto form a primary parallel linkage system with such pivots forming aparallelogram with the lever pivots, link means connecting the free endsof the other arms of the bell crank levers to form a secondary parallellinkage system such pivots also forming a parallelogram with the leverpivotssand mean -holdin .itlierbel i allkflf lfilffia n one side of thesuperstructur parallel. Wit Qnltheother-side '1 2. Elevating,,"apparatus, according to claim. 1 including aaalen thenompensatingshackle link connectingthez platformtoone lever armoneach side of theplatform, the :bellcranks being ofjsuch angle that. in the position ofhalf elevation .of the platform the secondary; parallel vlinkage systemforms. azrectangularifigurez. :rg-I 1 3 Elevating apparatus.according-t0 claim 1, including a length-compensating shackle linkconnecting the platform to one lever arm on each side of the platform,thelbell' cranks being of h angle a nithe nositiqn:o ih l eleva of theplatform the secondary parallel linkage system forms a rectangularfigure and further characterised by means at one of the pivots forvarying the distance between a pair of horizontally related pivots ofthe secondary linkage system whereby the lever arms of both systems aremoved out of parallel and the level of the platform thereby varied whilein any of its positions of elevation, the length-compensating meanspermitting the forward arms of the bell crank levers to pass through outof parallel. V

4. Elevating apparatus according to claim 1 wherein the platform issupported at each end of its transverse center line by one pivot of theforward arms of the front bell crank levers.

5. Elevating apparatus according to claim 1 wherein the platform issupported at each end of its transverse center line by one pivot of theforward arms of the front bell crank levers and wherein the forward armsof the front bell crank levers are cranked so as to lie below theplatform when in the lowered position.

6. Elevating apparatus according to claim 1 wherein the platform issupported at each end of its transverse center line by one pivot of theforward arms of the front bell crank levers and wherein mechanicalelevating means is located between the base and'the said forward arms ofthe front bell crank levers.

7. Elevating apparatus according to claim 1 further characterised inthat the means for holding the bell crank levers on one side parallelwith those on the other side comprises shafts extending betweenimmediately opposite bell crank levers.

8. Elevating apparatus according to claim 1 further characterised inthat the arms of the bell crank levers forming parts of the secondaryparallel link system are inwardly bent towards each other and connectedby a common link.

9. Elevating apparatus comprising a base, an elevated superstructure onsaid base having front and rear sides, a movable platform, front and,

rear bell crank levers pivoted intermediate their ends onhorizontallyspaced pivots on said superstructure, the lower arms of saidlevers extending downwardly and forwardly in parallel relation andpivoted to said platform, the upper arms of said levers extendingupwardly and forwardly in parallel relation, a link joining said upperarms, said link being parallel to the line joining said horizontallyspaced pivots, said upper arms ibeing shorter than said lower arms.

10. Elevating apparatus according to claim 9 further characterized inthat a shackle is interposed between one of said levers and saidplatform, and a lever actuated means for varying the effective length ofsaid link.

11. Elevating apparatus according to claim 9 further characterized inthat a hydraulic ram mounted on said base is directly connected to one12. Elevating apparatus accerding to cream 'I' further characfierizediinthat a'nshackle is: interp'osd btween oziez'oi saw levers and saidiplatfdrm and air-lever actuatecrmeansifor varying the m'memmg bpairatus-accondingi 1' 0" clai mr' 'r further characterized. in that ahyzi'nau-liz; mm

' mounted on said base i directly oflnectedtqofie of said levers at:apairit between 'said platfeml

